Conventionally, in a low-molecular organic electroluminescent device, carriers are smoothly injected into a light emitting layer using a multi-layered structure formed with a dry process. In an organic electroluminescent device using polymeric materials, on the other hand, polymer layers are formed with a wet process. With the commonly used wet process, however, a polymer layer serving as a lower layer is subjected to dissolution during the formation of a polymer layer as an upper layer.
For this reason, an organic electroluminescent device of the two-layered structure has been proposed in which two layers, a water-soluble conductive polymer and a luminescent polymer soluble in an organic solvent, are formed. Also proposed is the formation of a stacked structure using two kinds of solvents, a polar solvent and a non-polar solvent.
In addition, a method of fabricating an organic electroluminescent device has been proposed in which an organic material is used as a material of the light emitting layer which is soluble in a solvent having solubility parameters out of the solubility range for the material forming a first organic layer on the side of the substrate, and an organic material is used as a material of a second organic layer formed on the light emitting layer which is soluble in a solvent having solubility parameters out of the solubility range for the material forming the light emitting layer, so as to produce a multi-layered structure (refer to JP 2002-299061 A, for example).
The above-described prior art, however, has yet to provide an organic light emitting device with sufficient luminous efficiency.